1. Field of the Invention
The present invention relates to a power supply circuit of a display device and a display device using the power supply circuit. In particular, the present invention relates to a power supply circuit and a display device that enhance power efficiency during a write operation of display data.
2. Description of the Related Art
In order to boost a voltage in a power supply portion in a driving circuit for a display device for driving a liquid crystal panel, a switching regulator capable of eliminating a power loss and obtaining power with high precision and high efficiency is used. A power supply circuit using a switching regulator charges a coil with charges corresponding to an input voltage and discharges the charged charges from the coil, thereby boosting a voltage. At this time, the charging and discharging periods for charging and discharging of the charges of the coil are regulated in accordance with a ratio of an ON/OFF time of a switching element using a MOS-FET or the like (duty ratio), and an output voltage is determined based on the duty ratio.
As the power supply circuit using a switching element, there is a power supply circuit disclosed in JP 2000-278938 A. The power supply circuit sets a target voltage to be supplied to a load, compares an output voltage with the target voltage, and prolongs a time for accumulating power in a coil that is accumulation means at a high load, thereby generating a desired output voltage.